The present invention relates to appliance door latch constructions, and particularly to door latch strike assemblies suitable for use in the latching mechanism of an access door of a laundry appliance, e.g., an automated laundry washing machine.
Automated washing machines (such as laundry washing machines) typically include a door that swings open and shut to permit access to the wash basin or drum, for placement of wash load items in the drum at the initiation of the wash process and removal of the wash load items upon completion of a wash operation. Automated laundry dryers typically have a similar arrangement of door and access opening. Various types of latch assemblies are utilized to securely hold the door shut. This may include a safety interlock system to prevent opening of the door during certain operation cycles such as during a high-speed spin of a washer. Such door latch systems (whether with or without a safety interlock) typically include an elongate “strike” that protrudes from one of the door and the door receiving frame defining the access opening. The strike is configured to be engagingly received in a latch incorporated into the other one of the door and door receiving frame.
Consumers have certain expectations when it comes to the forces required to open and close laundry appliance access doors. Under the extreme tolerance stacks that come into play in the manufacture/assembly of a laundry appliance, dimensional variances within specified tolerances may add cumulatively causing dimensional variances in the alignment and relative positioning of the latch and the mating strike. In turn, this may lead to excessive forces being required for opening and/or closing the door, e.g., forces that are outside of desired marketing specifications. The situation is exacerbated in the case of an access door that is pressed shut against a compressible door bellow, seal gasket or the like provided in order to prevent leakage of liquid from the wash chamber (or heated air from a dryer). In this case, it is necessary that a certain amount of force be applied to press against the bellow or gasket sufficiently to obtain a fluid-tight seal. On the other hand, the closure force cannot be so high as to render it difficult for a user to manually effect the closure. A further difficulty is encountered in the case that it is desired to use a push to open, push to close (push-push) style door/latch in such an application. In this case, since the latch requires a relative inward (push) displacement of the strike from its normal closed door position, in order to open the door, the gasket will have to be further compressed, and if the strike extension depth is not correct to a fairly precise degree, operational difficulties are likely to be encountered. In particular, the further compression of the seal gasket necessary to move the strike sufficiently to actuate release of the push-push latch may require a user to exert more force than would be desirable. The amount of bellow/gasket compression required to effect latching (or unlatching), and hence the closure force required to secure the door shut (or open it), is directly impacted by the extension depth of the strike from the door. If the point that must be reached to latch or unlatch the door is significantly beyond a point where the door begins to compress the main front face of the bellow, this adds significant opposing forces with little inward movement of the door assembly. On the other hand, if there is excessive strike extension, the seal/bellow may not be adequately pressed by the door, resulting in an inadequate seal and leakage potential. There is no easy fix in the case that the force required to open/close the door is excessive due to insufficient strike extension, or if there is an inadequate seal/leakage potential due to excessive strike extension. Parts would need to be replaced or hand modified/adjusted to reach desired door forces.
Some previous attempts have been made to deal with misalignments that can arise between door strike and latch structures.
U.S. Pat. No. 6,685,241 discloses a closing device for a laundry appliance which includes a strike (“closing piston”) mounted to the machine door with pins within horizontally aligned slots, to effect automatic strike/latch alignment upon door closure.
DE 19636925 discloses a locking element (“clamp (12)”) of a washing machine lid that “is mounted on or in an underplate (8) of the lid in such a way it moves within limits across its closing direction.” English Abstract.
U.S. Pat. Nos. 7,240,931 and 5,118,151 both disclose a slide mount of door strike elements (not an appliance door); the '931 patent discloses a strike plate horizontally slideable in channels located on a base plate.
U.S. Pat. No. 6,679,572 discloses a lid or door for a laundry appliance that employs a push-push latch and a gas-charged cylinder for extending the door to an open position upon release of the latch. This patent does not address the issue that can arise with an attempt to use a push-push actuated access door with a compressible seal gasket or bellow. While front load appliances are mentioned, the illustrated top load washer embodiment would inherently have much less need for a strong liquid-tight seal as compared to a front load washer.
There is a need for a technique and door/latch structure to deal efficiently and effectively with the excessive door closure forces and other potential complications that can arise in the case that the door strike extension depth is not ideally matched to the relative location of the mating latch mechanism. This would be particularly useful to render feasible and reliable the use of a push-push style access door that must be compressed against a compressible door bellow or seal gasket in order to effect both opening and closing of the door.